Guys I am lost and need help. My blazer(91 4.3 auto 4wd 150000) stalls and backfires on take off, will not do 65 unless I keep pedal to the floor. Replaced all sensors, fuel pump,pressure regulator,plugs,egr valve,iac valve, distr cap, rotor . Not setting off any codes at all. Have aftermarket coil (accel), 8mm plug wires less than a year old. Idles fine just will not go up a hill without pedal to the floor. with cruise on it drops speed till cruise shuts off. I am to the point of selling it in parts right now. Very frustrating and expensive. Oh yeah changed out computer also. Spark control mod too. Any ideas?

Forgot to mention my troubles all started when I changed oil. Run synthetic 5w30, and changed air filter and fuel filter when I changed the oil. Drive aprox 60 miles per day, all hiway.

 

not insult you or anything but did you install the fuel filter the correct way. With the FLOW arrow pointing towards the front of the truck. Sounds like a fuel problem to me.

Do you have a TBI or CPI engine? It could be your Fuel Injector connection, the wired connection that connects to the top of the Spyder. The rubber bushing turns to mush from being exposed to fuel and loosens the connection.

 

Yes i installed fuel filter correctly. It`s got the 220 tbi . I keep thinking spark but really don`t know. When going down the hiway it will not maintain speed. either speeding up or slowing down. Has to kick into passing gear to increase speed even 2 mph. Keeping steady pressure on pedal and speed drops. Feels like choke is stuck, if it had a carb that is. One funny thing , when I changed fuel filter gas ran out from the time I unhooked old one until I had new one in. Never ran out like that last time I changed it.

 

Sounds fuel related to me as well. The TBI has a fuel pressure regulator built into it. The purpose is to maintain the proper fuel pressure for the injectors which is about 11 PSI. If you get a TBI rebuild kit you will get a new spring and diaphram for the regulator. It is easy to install. If the pressure at the TBI is correct then I would suspect the injectors. Faulty injectors will not through a code unless they have an electrical problem. I installed an adjustable regulator and a in line fuel pressure gage so I can check my fuel pressure any time I desire. The fuel presssure regulator is bolted to the underside of the fuel meter cover. The Haynes manual has a good exploded view of the 220 TBI. I do not believe you can get the spring and diaphram without buying a rebuild kit. I got my rebuild kit from NAPPA. Hope this helps. The TBI engines do not have a built in test port to check fuel pressure. In order to check you have to break the fuel lines and install a gage in line. I had purchased a fuel pressure kit for the TBI a long time ago from JC Whitney. The place I was able to install it was at the frame where the lines come through before heading up to the engine.

 

Pressure regulator replaced a few months ago along with gaskets. Injectors seem to have a good spray pattern. I have not checked the fuel pressure but will do. Thanks for the help, this blazer has got me pulling my hair out.

ok, did the pressure test and have 11 psi. Did not hold pressure but went back to zero as soon as engine shut off.

 

changed pressure regulater, didnt help. set of injectors will be in tomorrow so am hoping that will get it fixed, Am wondering if timing could be the problem?

 

Just did a test drive after changing the injectors. No luck, runs as bad as before. So that rules out fuel ,any ideas anyone? 9-30 Took The tank off today and changed all fuel lines, nothing in tank, fuel pump hooked up correct and sock ok. Pulled plugs, distributor cap and rotor. All good. Truck still has no power back, fires on take off. .Next will check cat out and see if it`s plugged. Am wondering about a weak coil maybe though no trouble with starting. Mild surge at idle but not bad.

 

It was the catalytic converter. Was partially plugged up. Blazer running great again, only problem now is the bald spots from where I pulled my hair out!